This research is aimed at an elucidation of some important structural features of the bacterial ribosome. Of principle interest is the relative locations of the ribosomal proteins and the proximities of these to important functional sites. In addition to structural information, we hope to obtain a more detailed picture of the mechanism of protein synthesis. Included in this is the mode of action of several common antibiotics. Simple chemical modification techniques afford information on topography of ribosomal proteins. Affinity labeling will be used to identify proteins in particular functional sites. Singlet-singlet energy transfer can measure distances between appropriate fluorescent-labeled ribosomal proteins or sites. Individual fluorescent proteins are reassembled to give single or double fluorescent labeled ribosomes. Other markers can be introduced by preparing functionally active fluorescent substrate analogs or antibiotics. Protein distances may also be measurable by photocrosslinking reagents.